Internal combustion engines currently include an alternator and a starter motor. The starter motor provides a starting torque to the crankshaft of the engine in order to facilitate the ignition of the engine. The alternator or generator generates an electrical output for meeting the electrical loads of the vehicle, as well as to charge the vehicle's battery.
The concept of using only one electric machine to do both functions, namely starting and generating, adds efficiency. Efficiency is increased because such starting and generating electric machines eliminate the cost of one of the machines and reduce assembly time. It has been proposed to place the combination starting and generating electric machine between the internal combustion engine and the transmission of a hybrid vehicle.
In order to properly assemble the components of such an electric machine, a rotor that is secured to the crankshaft must also be disposed concentrically within a stator. Thus, the rotor is rotatably received within the opening defined by the stator. Therefore an outer surface of the rotor and the inside diameter of the stator are separated by a substantially uniform, precise air gap, across which the magnetic flux generated by the components of the electric machine travels. Thus, and in order to ensure specific performance of the electric machine, the size of the air gap must not vary outside predetermined tolerances. Accordingly, the installation of such components in a hybrid vehicle requires forming a precise air gap between the rotor and the stator.
Currently, the stator and the rotor are aligned using techniques that require either the use of shims (e.g., trial and error assembly), or the use of specially designed and constructed stator/rotor components. Thus, there is a continuing need for apparatus and methods for aligning component parts of an electric machine.